In a conventional optical device, by using a lens, spherical waves radiated from a point light source located at a focal point of the lens may be turned into plane waves after refraction of the lens. A lens antenna is an antenna that consists of a lens and a radiator placed on the focal point of the lens, and uses the lens to converge electromagnetic waves radiated from the radiator based on a converging property of the lens and emit the converged waves. This type of antenna is strong in directivity.
Currently, the convergence of the lens is achieved by refraction of a spherical shape of the lens. As shown in FIG. 1, spherical waves emitted from a radiator 1000 are emitted as plane waves after convergence by a spherical lens 2000. The inventors have identified that during the implementation of the present invention that, the lens antenna has at least the following technical problems: the spherical lens 1000 is large in volume and heavy, which is not favorable to miniaturization; the spherical lens 1000 depends heavily on the shape, and direction propagation of the antenna can be realized only when the shape is very accurate; and reflection interference and loss of the electromagnetic wave are quite severe, and electromagnetic energy is reduced. When the electromagnetic waves pass through boundary surfaces of different media, a phenomenon of partial reflection may happen. Usually, the larger the difference in electromagnetic parameter (permittivity or conductivity) between two media, the larger the reflection is. Due to reflection of partial electromagnetic waves, electromagnetic energy along a propagation direction may lose correspondingly, which seriously affects a propagation distance of electromagnetic signals and quality of transmitted signals.